Journal Archives - Volume 4
Editorial: The urinary bladder is unique. As a follow organ, it demonstrates a remarkable integration of neuromuscular and mechanical-physical properties which are crucial to the normal function of the bladder. No other organ is evolutionarily programmed to fill with fluid over hours at low pressures, and then contact on demand to evacuate its contents. Indeed, the sociobiologic etiology and reasons for the existence of this unique behavior has been argued for decades. While the ability to accommodate a fluid volume (filling) is largely a passive phenomenon, this is not entirely the case. Recruitment of active neuromechanical properties are crucial to maintenance of low intravesical pressures during filling, and to this end the physicochemical nature of the surrounding extracellular matrix (ECM) can either facilitate or impede this function. Bladder contraction (emptying), on the other hand, is largely an active neuromuscular process, though it too is influenced by the physico-chemical nature of the ECM, and by bladder smooth muscle cells (bSMC) overall mass.
Posterior urethral obstruction continues to be a significant cause of morbidity, mortality, and ongoing disability in the pediatric age group. Boys with obstructive uropathy and dysplasia represent the single largest group of children undergoing renal dialysis and transplantation under five years of age. Even with this clinical significance, and the fact that the condition has been recognized for well over 150 years, our understanding of the embryology and developmental anatomy of the male posterior urethra remains limited. With the advent of new technology and diagnostic tools, traditional theories of the obstructive anatomy have recently been challenged in the pursuit of a clearer understanding of the mechanism of obstruction.
With the advent of routine antenatal ultrasound screening, the detection and diagnosis of fetal urological abnormalities has become a major challenge. Fetal kidneys can be identified as early as 12 weeks and are clearly seen by 14 to 15 weeks. Major urological abnormalities present early during the pregnancy, however, most subtle abnormalities may present late in the gestation. The incidence of fetal uropathy detected by routine pre-natal ultrasonography varies from 1 in 154 pregnancies reported from stoke on Trent in the United Kingdom, to 1 in 1200 from Lund, Sweden, in different series.
Posterior urethral valves (PUV) are the commonest cause of obstructive uropathy which leads to renal failure in childhood. PUV represents a disease spectrum with varying severity and has profound effects on the bladder as well as the upper tracts. Though the short-term outcome for boys with PUV is presently very good, long-term prognosis is still far from satisfactory. The incidence of end stage renal disease (ESRD) in valve patients varies between 24-33% depending on the duration of follow-up.
Congenital bladder outlet obstruction by posterior urethral valve is associated with a constellation of changes in the urinary tract extending from kidney to the urethra. Histologically both the treatment and clinical outcome of patients with valves has been quite variable. Prior to routine prenatal screening by obstetric ultrasound diagnosis was commonly delayed, coming only after patients presented with urosepsis on renal failure. Patient treatment focused on prevention of urinary sepsis with temporizing surgical procedures done to maximize urinary drainage. Severe hydroureteronephrosis, persistent reflux and poor endoscopic instrumentation drove a rend toward urinary diversion in many surviving infants. Subsequently such patients would undergo multiple surgical procedures including undiversion, urethral reimplantation and bladder augmentation, only to end up in adolescence with persistent upper tract stasis, poor bladder function and renal failure.
At the Children's Hospital of Philadelphia, primary valve ablation and vesicostomy have allowed most patients with posterior urethral valves (PUV) to avoid bladder augmentation. We review the outcome of 13 patients with PUV who have undergone 15 renal transplants. A significant increase in graft loss was seen in patients initially managed with high diversion compare to patients who underwent valve ablation or vesicostomy. At a median follow-up of 2 years (range: 6 months–14 years) after transplant, no significant difference was found in graft function or somatic growth, based on initial bladder management. When, necessary, we recommend renal transplantation into a bladder with a vesicostomy, rather than performing continent diversion prior to transplant. This allows the patient to manage his own catheterization, and also avoids the risk of impaired growth due to bowel augmentation in a young child. The optimal prenatal management is not yet determined, but in utero ablation of PUV is a tantalizing possibility, if our understanding of bladder cycling can be improved.
Posterior urethral valves (PUV) are the most common form of congenital urethral obstruction, with an incidence varying from 1in 8,000 to 25,000 male births. Obstruction induces a global injury to almost the entire urinary tract, and the urethral distal to the valves seems to be the only unaffected segment. So far the kidneys are the organs to receive most attention, since the foremost goal of any treatment to patients with PUV is to maintain and maximize renal function. Increasing evidence emerges on the central role of bladder function (or dysfunction) in the natural history of valve patients, leading to everlasting debates on different therapeutic approaches and their effect on future bladder function and even on the eventual outcome. It is unquestioned that the bladder is no longer an "intermediate" between valvular obstruction and kidney damage but a constantly changing and long-acting factor in the impairment of urinary tract function.
Upper tract prognosis in posterior urethral valve patients has been investigated from a number of aspects including mortality rate, onset of chronic renal failure, onset of end-stage real disease and persistence of upper tract dilatation. Overall prognosis has improved tremendously over recent decades due to a combination of factors including in utero ultrasound diagnosis, elective termination of pregnancy of the more severe cases and better perinatal care. In reports prior to 1970 perinatal mortality was in the rage of 50 percent most often was secondary to respiratory failure, sepsis, acidosis and uremia. Those with the most severe disease, particularly those with severe oligohydramnios and dysplasia, have the worst prognosis and die of respiratory failure.
Posterior urethral valves (PUV) are the most common obstructive uropathy leading to childhood renal failure. The spectrum of severity for this disorder ranges from incompatible with survival when the patient dies shortly after birth, to minimal voiding disorders in patients who present in late childhood with a normal renal function. Paradoxically, the recent increases in survival of boys with PUV, especially the most severely affected, will mean that more children with the condition will eventually require renal replacement therapy. The increased frequency with which valves are being identified in utero provides pediatric urologists with the opportunity to undertake optimal treatment before the lingering effects of obstruction; bladder dysfunction or additional damage from infection can be established. It is imperative that management strategies be directed at maximizing renal function in later life.
Posterior urethral valves is a heterogeneous disorder that varies significantly in severity with an incidence of 1 in 4000–7500 infant males. Chronic renal failure occurs in a significant number of children with posterior urethral valves and account for 16.8% of the population of children with end stage renal disease necessitating renal transplantation. Congenital obstruction of the posterior urethra may induce structural and functional bladder changes that include increased bladder wall thickness, increased collagen deposition, decreased compliance, and diminished effective emptying. These bladder changes impact upper urinary tract physiology by means of transmitting abnormality high pressures to the renal parenchyma. In addition, patients with severe posterior urethral valves are believed to have renal congenital dysplasia that may not be secondary to reflux or back pressure but rather may result from embryological changes that includes abnormal caudal budding of the ureter off the nesonephric duct and subsequently abnormal induction of mesenchymal growth.
Proximal urinary diversion in the treatment of congenital posterior urethral obstruction has recently fallen out of favor, with many now recommending primary ablation of the obstructive lesion. There still remains however, a group of patients who continue to deteriorate despite lower urinary decompression, with evidence of vesico-ureteric junction obstruction or a high pressure bladder. In these patients the role of high diversion remains unclear. We describe the use of a temporary nephrostomy and ureteric stenting as a less aggressive and easily reversible method of decompressing the upper urinary tracts, to achieve improvement in renal function and hydronephrosis without the use of more permanent diversion techniques.
The magnet of the newborn with posterior urethral valves (PUV) and renal insufficiency remains controversial. Previously, many authors advocated early supravesical diversion in order to maximize renal recover. Others have advocated vesicostomy for the same purpose. More recently, some authors have strongly supported the role of bladder cycling in preventing the development of a "hostile" high pressure bladder and recommend avoidance of supravesical diversion. While the issue of diversion remains controversial, the effects of uremia on growth and development are clearly documented. Early recognition of the onset of significant renal insufficiency is essential, with prompt involvement of the pediatric nephrologist had attention directed at nutrition, correction of acidosis, maintenance of red cell mass (crythropoetin), stabilization of bone density (vitamin D,) maximization of growth (rhGH) and application of dialysis when indicated. Clearly, elevated bladder pressures have an adverse effect on upper tract integrity, and diversion in those patients whose bladder pressures cannot be controlled with other interventions, may not have an adverse effect on ultimate bladder function.
Numerous surgical techniques have been described for the correction of hypospadias. In recent years, one-stage operations have increasingly been favored and are now exclusively the method of choice for distal hypospadias. However, severe types of proximal hypospadias present several features that pose difficulties in surgical correction. Chordee is often very severe and may require combined procedures for complete correction. The penis is generally short and not well developed. In addition, it is tethered to perineal tissues giving it a buried appearance. Preputial skin may not be adequate enough to reconstruct the urethra and bring the metal opening to the tip of the glens. The scrotum may be bifid with penoscrotal transposition. Based on previous work done by the author a new approach to single-stage urethroplasty in proximal hypospadias was developed and has been successfully employed. Details of the technique are presented and illustrated.